Compares two contract versions side-by-side to detect added, removed, and modified clauses with favorability analysis. Use when a user receives a revised contract or redline and needs to understand what changed and who each change favors. Trigger with "/contract-compare" or "compare these two contracts".
Side-by-side contract comparison skill that identifies every change between two versions, classifies each change by type and severity, and determines which party each modification favors. Essential during negotiation rounds when a counterparty returns a revised draft.
When a counterparty returns a revised contract, the changes they made — and the changes they quietly did not make — tell a story about their priorities and strategy. This skill performs a structured comparison that surfaces not just what changed, but the strategic significance of each change.
It detects three dangerous patterns that manual review frequently misses: indemnification drift (gradual shifting of liability across revisions), IP scope creep (expanding intellectual property assignment through small wording tweaks), and definition manipulation (redefining key terms to alter clause meaning without touching the clauses themselves).
contract-v1.pdf and contract-v2.pdf)Ingest both versions. Read each document in full. If file paths are provided, use the Read tool.
Establish the structural map. Create a section-by-section outline of both documents. Note any structural changes (sections added, removed, renumbered, or reordered).
Perform clause-level comparison. For each section, classify changes into:
| Change Type | Symbol | Description |
|---|---|---|
| Added | + | Entirely new clause or section |
| Removed | - | Clause present in original but absent in revision |
| Modified | ~ | Wording changed within an existing clause |
| Moved | -> | Same content relocated to a different section |
| Unchanged | = | No material difference |
Analyze favorability. For each non-trivial change, determine:
Detect dangerous patterns. Specifically scan for:
Calculate the favorability balance. Tally all changes by which party they favor and the severity weight:
Party A Score = (Major changes favoring A x 3) + (Moderate x 2) + (Minor x 1)
Party B Score = same formula for B
Balance: A-favored / B-favored / Balanced
Generate the comparison report with all findings organized by section.
Filename: CONTRACT-COMPARISON-{YYYY-MM-DD}.md
# Contract Comparison Report
## Documents Compared
| | Version A (Original) | Version B (Revision) |
## Summary of Changes
| Change Type | Count |
## Change Log (by section)
| Section | Change Type | Description | Favors | Severity |
## Dangerous Pattern Alerts
## Favorability Balance
## Silent Removals
## Negotiation Strategy Recommendations
## Disclaimer
| Failure Mode | Cause | Resolution |
|---|---|---|
| Documents are unrelated | Two entirely different contracts provided | Warn the user and ask for confirmation before proceeding |
| Structural mismatch | Different section numbering schemes | Map sections by content, not by number |
| Missing version identifier | User did not specify which is original | Ask which version is the baseline |
| Partial document | One version is incomplete or truncated | Note the gaps; compare only overlapping sections |
| Format mismatch | One is formatted text, other is raw | Normalize both to plain text before comparing |
Example 1 — MSA negotiation round:
User: Compare ~/contracts/acme-msa-v1.pdf with ~/contracts/acme-msa-v2.pdf
Summary: 14 changes detected across 23 sections.
Key Changes:
1. Section 5.1 (IP Assignment) [MODIFIED] — Severity: MAJOR
Original: "Work product created under SOW is assigned to Client"
Revision: "Work product created in connection with the engagement
is assigned to Client"
Favors: Client | Signal: Expanding IP scope beyond SOW deliverables
2. Section 8.3 (Liability Cap) [MODIFIED] — Severity: MAJOR
Original: "Liability capped at 12 months of fees paid"
Revision: "Liability capped at fees paid in the preceding 3 months"
Favors: Vendor | Signal: 75% reduction in liability exposure
3. Section 2 (Definitions) [MODIFIED] — Severity: MAJOR
"Confidential Information" definition expanded to include
"business strategies and future product plans" — broadens
confidentiality obligations without touching Section 7.
DANGEROUS PATTERN: Definition manipulation detected.
The revision altered 3 defined terms that collectively change
the meaning of 7 other clauses without modifying those clauses.
Favorability Balance: 9 changes favor Client, 4 favor Vendor, 1 Neutral
Overall Tilt: Client-favored revision
Example 2 — Employment agreement revision:
User: My employer sent back a revised offer. Compare the original with this new version. [pastes both]
SILENT REMOVAL ALERT:
Original Section 4(d) — "Employee may terminate with 2 weeks notice
for any reason" — has been removed entirely. The revision contains
no voluntary termination provision for the employee, while the
employer retains at-will termination rights in Section 4(a).
Legal Disclaimer: This skill provides AI-generated contract comparison for informational and educational purposes only. It does not constitute legal advice, create an attorney-client relationship, or substitute for consultation with a qualified attorney. Comparison accuracy depends on the quality of input documents and may miss changes in formatting, embedded objects, or metadata. Always consult a licensed attorney before acting on comparison findings.